The quality of EDTA calcium products on the market varies greatly. Some low-priced products have problems such as low chelation rate, mixed inorganic calcium and excessive impurities. Mastering 4 core standards can quickly identify high-quality products.

First, check the appearance and water solubility. High-quality EDTA chelated calcium is white uniform crystalline powder, no caking and no impurities. Add 1g of sample to 100ml of room temperature clear water, it should dissolve quickly and completely after stirring. The solution is clear and transparent, no precipitation and no scum, and water insoluble matter should be less than 0.1%. If it dissolves slowly with much residue, it is probably an inferior product mixed with calcium nitrate.

Second, verify calcium content and chelation rate. Regular agricultural grade EDTA chelated calcium contains ≥10% chelated calcium, and the chelation rate should be ≥98%, meaning most of the calcium is chelated and wrapped by EDTA molecules. Some merchants claim that the total calcium content meets the standard, but the actual chelation rate is low with much free calcium, which is easily fixed by soil after application and greatly reduces the effect.

Third, confirm the pH stability range. High-quality EDTA calcium is stable and effective between pH 4.0-9.0. You can ask for product stability test reports to check the chelate retention rate at different pH values. If the product claims to be long-term stable in strongly alkaline soils, be alert to false publicity.

Fourth, pay attention to impurity indicators. High-quality agricultural grade EDTA calcium has low heavy metal content, and arsenic, lead, cadmium and other elements all meet the limit standards of agricultural fertilizers, which will not cause soil pollution and crop residues. Prioritize factory sources with formal third-party test reports and stable production capacity to ensure product batch stability and application effect.